Bacterial ecology and rheological parameters of multigrain gluten-free sourdoughs

The microbial diversity and pasting properties of three sourdoughs produced from composite gluten-free flours were investigated using 16S rRNA gene clone libraries and the Rapid Viscoanalyser. Finger millet-pearl millet (FP), Pearl millet-sorghum (PS) and Finger millet-sorghum (FS) sourdoughs were produced. Eleven aerobic bacteria and twelve lactic acid bacteria (LAB) were randomly selected from the sourdoughs. Presumptive Bacillus subtilis and Pediococcus spp. were identified in all the sourdoughs after 48 h of fermentation, while yeast was not detected in any of the products. The LAB population and pH ranged from log 7.70 CFU g(-1) to log 10.52 CFU g(-1) and 3.8 to 4.2 respectively. The findings showed that well-developed sourdough could be produced from these composite flours by spontaneous fermentation. Significant differences were observed in the pasting properties of all the sourdoughs. Decline in the tendency to retrograde occurred in all sourdoughs, thereby justifying the lower staling rate of final products. This study enhanced the corpus of existing knowledge on the microbial diversity of gluten-free sourdough and provided a basis for the possible application of Pediococcus spp. and Weisella spp. as a starter culture(s) in fermented products.